Strain sensing element, pressure sensor, microphone, blood pressure sensor, and touch panel

ABSTRACT

According to one embodiment, a strain sensing element provided on a deformable substrate, includes: a first magnetic layer; a second magnetic layer; and an intermediate layer. The second magnetic layer includes Fe 1-y B y  (0&lt;y≤0.3). Magnetization of the second magnetic layer changes according to deformation of the substrate. The intermediate layer is provided between the first magnetic layer and the second magnetic layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 14/333,906 filed Jul. 17, 2014, which is based upon and claims thebenefit of priority from Japanese Patent Application No. 2013-196081,filed on Sep. 20, 2013; the entire contents of which are incorporatedherein by reference.

FIELD

Embodiments described herein relate generally to a strain sensingelement, a pressure sensor, a microphone, a blood pressure sensor, and atouch panel.

BACKGROUND

A pressure sensor that uses a MEMS (Micro Electro Mechanical Systems)technology includes, for example, a piezoresistance change type and anelectrostatic capacitance type. On the other hand, a pressure sensorthat uses a spin technology has been proposed. In the pressure sensorusing the spin technology, a resistance change corresponding to strainis sensed. The sensitivity of the resistance change corresponding to thestrain depends on a material of a spin valve film, for example. Forexample, in a strain sensing element that is used in the pressure sensoror the like using the spin technology, it is desirable to enhance thesensitivity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1C are schematic diagrams illustrating a strain sensingelement according to a first embodiment;

FIGS. 2A to 2C are schematic diagrams illustrating the operation of thestrain sensing element according to the first embodiment;

FIGS. 3A to 3C are graphs illustrating an example of an experimentalresult of the strain sensing element according to the embodiment;

FIGS. 4A to 4C are graphs illustrating an example of anotherexperimental result of the strain sensing element according to theembodiment;

FIGS. 5A to 5C are graphs illustrating examples of other experimentalresults of the strain sensing element according to the embodiment;

FIGS. 6A to 6C are graphs illustrating examples of other experimentalresults of the strain sensing element according to the embodiment;

FIGS. 7A to 7C are graphs illustrating examples of other experimentalresults of the strain sensing element according to the embodiment;

FIGS. 8A to 8C are graphs illustrating examples of other experimentalresults of the strain sensing element according to the embodiment;

FIGS. 9A to 9D are graphs illustrating examples of other experimentalresults of the strain sensing element;

FIGS. 10A to 10D are graphs illustrating examples of results of strainsensor characteristics of the strain sensing element according to theembodiment;

FIG. 11A and FIG. 11B are schematic diagrams illustrating another strainsensing element according to the first embodiment;

FIG. 12A and FIG. 12B are schematic perspective views illustrating apressure sensor according to the second embodiment;

FIGS. 13A to 13E are schematic cross-sectional diagrams sequentiallyillustrating the process of the method for manufacturing the pressuresensor according to the embodiment;

FIG. 14 is a schematic plan view illustrating a microphone according toa third embodiment;

FIG. 15 is a schematic cross-sectional view illustrating the acousticmicrophone according to a fourth embodiment;

FIG. 16A and FIG. 16B are schematic views illustrating the bloodpressure sensor according to a fifth embodiment; and

FIG. 17 is a schematic plan view illustrating a touch panel according toa sixth embodiment.

DETAILED DESCRIPTION

In general, according to one embodiment, a strain sensing elementprovided on a deformable substrate, includes: a first magnetic layer; asecond magnetic layer; and an intermediate layer. The second magneticlayer includes Fe_(1-y)B_(y) (0<y≤0.3). Magnetization of the secondmagnetic layer changes according to deformation of the substrate. Theintermediate layer is provided between the first magnetic layer and thesecond magnetic layer.

Hereinafter, embodiments of the invention will be described withreference to the accompanying drawings.

The drawings are schematic or conceptual; and the relationship betweenthe thickness and the width of each portion, the proportion of sizesbetween portions, or the like is not necessarily the same as in actualportions. Further, the dimensions and/or the proportions may beillustrated differently between the drawings, even for identicalportions.

In the drawings and the specification of the application, componentssimilar to those described in regard to a preceding drawing are markedwith like reference numerals, and detailed description thereof isomitted as appropriate.

First Embodiment

FIGS. 1A to 1C are schematic diagrams illustrating a strain sensingelement according to a first embodiment.

FIG. 1A is a schematic perspective view of the strain sensing element.FIG. 1B is a schematic cross-sectional view of the strain sensingelement. FIG. 1C is a schematic cross-sectional view illustrating apressure sensor in which the strain sensing element is used. In FIG. 1B,for ease of description, a first electrode and a second electrode arenot shown.

As illustrated in FIG. 1A, a strain sensing element 100 according to theembodiment includes a first magnetic layer 10, a second magnetic layer20, and an intermediate layer 30. In the example, the strain sensingelement 100 further includes a functional layer 40, a first electrodeE1, and a second electrode E2. The functional layer 40 may not beprovided.

For example, a direction from the first magnetic layer 10 to the secondmagnetic layer 20 is taken as a Z-axis direction (a stacking direction).One direction perpendicular to the Z-axis direction is taken as anX-axis direction. A direction perpendicular to the Z-axis direction andthe X-axis direction is taken as a Y-axis direction.

In the example, the second electrode E2 is separated from the firstelectrode E1 in the stacking direction. The first magnetic layer 10 isprovided between the first electrode E1 and the second electrode E2. Theintermediate layer 30 is provided between the first magnetic layer 10and the second electrode E2. The second magnetic layer 20 is providedbetween the intermediate layer 30 and the second electrode E2. Thefunctional layer 40 is provided between the second magnetic layer 20 andthe second electrode E2. The functional layer 40 includes a non-magneticlayer or any material except for a non-magnetic material.

The first magnetic layer 10 and the second magnetic layer 20 may beswitched in their positions with the intermediate layer 30 beinginterposed therebetween. In such a case, the functional layer 40 isprovided between the second magnetic layer 20 and the first electrodeE1.

The first magnetic layer 10 serves as a reference layer, for example. Amagnetization fixed layer or a magnetization free layer is used as thereference layer. As illustrated in FIG. 1A and FIG. 1B, the firstmagnetic layer 10 is a magnetization fixed layer. For example, the firstmagnetic layer 10 includes, for example, a synthetic pinned structure ora single pinned structure. In the example, the first magnetic layer 10includes the synthetic pinned structure. As described later, the firstmagnetic layer 10 may be a magnetization free layer.

In the example illustrated in FIG. 1A and FIG. 1B, the first magneticlayer 10 includes a first magnetization fixed layer 11, a secondmagnetization fixed layer 12, and a magnetic coupling layer 13. Themagnetic coupling layer 13 is provided between the first magnetizationfixed layer 11 and the second magnetization fixed layer 12.

The second magnetization fixed layer 12 includes, for example, aCo_(x)Fe_(100-x) alloy (x being 0 at. % or more and 100 at. % or less),a Ni_(x)Fe_(100-x) alloy (x being 0 at. % or more and 100 at. % orless), or a material in which a nonmagnetic element is added to thesealloys. For example, at least one selected from the group consisted ofCo, Fe and Ni is used as the second magnetization fixed layer 12. Analloy including at least one selected from these materials may be usedas the second magnetization fixed layer 12. The second magnetizationfixed layer 12 may include, for example, a(Co_(x)Fe_(100-x))_(100-y)B_(y) alloy (x being 0 at. % or more and 100at. % or less and y being 0 at. % or more and 30 at. % or less).

When the single pinned structure is used in the first magnetic layer 10,the same material as in the second magnetization fixed layer 12described above may be used as a ferromagnetic layer used in themagnetization fixed layer of the single pinned structure.

The magnetic coupling layer 13 causes antiferromagnetic coupling tooccur between the second magnetization fixed layer 12 and the firstmagnetization fixed layer 11. For example, Ru is used as the magneticcoupling layer 13. A material other than Ru may be used as the magneticcoupling layer 13 as long as the material can cause sufficientantiferromagnetic coupling to occur between the first magnetizationfixed layer 11 and the second magnetization fixed layer 12. For example,Ru having a thickness of 0.9 nm is used as the magnetic coupling layer13. Thus, highly reliable coupling is obtained stably.

A magnetic layer that is used in the first magnetization fixed layer 11contributes directly to a magnetoresistance effect (MR effect). Forexample, a Co—Fe—B alloy is used as the first magnetization fixed layer11. Specifically, a (Co_(x)Fe_(100-x))_(100-y)B_(y) alloy (x being 0 at.% or more and 100 at. % or less and y being 0 at. % or more and 30 at. %or less) may be used as the first magnetization fixed layer 11.

For example, an Fe—Co alloy other than the Co—Fe—B alloy may be used asthe first magnetization fixed layer 11.

Instead of the materials described above, the first magnetization fixedlayer 11 may include a Co₉₀Fe₁₀ alloy having an fcc structure, Co havingan hcp structure, or a Co alloy having an hcp structure. At least oneselected from the group consisted of Co, Fe and Ni may be used as thefirst magnetization fixed layer 11. An alloy including at least onematerial selected from these materials may be used as the firstmagnetization fixed layer 11. For example, a higher MR change ratio isobtained by using an Fe—Co alloy material having a bcc structure, a Coalloy including a cobalt composition of 50 at. % or more, or a materialhaving a Ni composition of 50 at. % or more (Ni alloy) as the firstmagnetization fixed layer 11.

For example, a Heusler magnetic alloy layer made of Co₂MnGe, Co₂FeGe,Co₂MnSi, Co₂FeSi, Co₂MnAl, Co₂FeAl, Co₂MnGa_(0.5)Ge_(0.5),Co₂FeGa_(0.5)Ge_(0.5), or the like may be used as the firstmagnetization fixed layer 11. For example, a Co₄₀Fe₄₀B₂₀ layer having athickness of 3 nm may be used as the first magnetization fixed layer 11.

The second magnetic layer 20 serves as a magnetization free layer, forexample. If stress is applied to the strain sensing element 100, strainoccurs in the strain sensing element 100, and thus, the magnetization ofthe second magnetic layer 20 is changed. For example, the change of themagnetization of the second magnetic layer 20 occurs more easily thanthe change of the magnetization of the first magnetic layer 10. Thus, arelative angle between the magnetization of the first magnetic layer 10and the magnetization of the second magnetic layer 20 is changed.

The second magnetic layer 20 may include a ferromagnetic material.

In the embodiment, the second magnetic layer 20 includes Fe_(1-y)B_(y)(0<y≤0.3). The entirety of the second magnetic layer 20 may be formed byFe_(1-y)B_(y) (0<y≤0.3). For example, Fe_(1-y)B_(y) (0<y≤0.3) may beprovided in a region that includes an interface 20 s between the secondmagnetic layer 20 and the intermediate layer 30 in the second magneticlayer 20.

The second magnetic layer 20 may include a material in which a part ofFe in Fe_(1-y)B_(y) (0<y≤0.3) is replaced with Co or Ni, that is,(Fe_(a)X_(1-a))_(1-y)B_(y) (0.8≤a<1, 0<y≤0.3). In the above-described(Fe_(a)X_(1-a))_(1-y)B_(y), X is Co or Ni. That is, the second magneticlayer 20 may include (Fe_(a)Co_(1-a))_(1-y)B_(y) (0.8≤a<1, 0<y≤0.3) or(Fe_(a)Ni_(1-a))_(1-y)B_(y) (0.8≤a<1, 0<y≤0.3).

The entirety of the second magnetic layer 20 may be formed by(Fe_(a)X_(1-a))_(1-y)B_(y) (0.8≤a<1, 0<y≤0.3). That is, the entirety ofthe second magnetic layer 20 may be formed by(Fe_(a)Co_(1-a))_(1-y)B_(y) (0.8≤a<1, 0<y≤0.3). Alternatively, theentirety of the second magnetic layer 20 may be formed by(Fe_(a)Ni_(1-a))_(1-y)B_(y) (0.8≤a<1, 0<y≤0.3). For example,(Fe_(a)X_(1-a))_(1-y)B_(y) (0.8≤a<1, 0<y≤0.3) may be provided in theregion that includes the interface 20 s.

The second magnetic layer 20 may include both of Fe_(1-y)B_(y) (0<y≤0.3)and (Fe_(a)X_(1-a))_(1-y)B_(y) (0.8≤a<1, 0<y≤0.3). In a case where X isCo, it is preferable that (Fe_(a)Co_(1-a))_(1-y)B_(y) (0.8≤a<1, 0<y≤0.3)be provided in the region that includes the interface 20 s.

The second magnetic layer 20 may include Co₄₀Fe₄₀B₂₀. In such a case,Co₄₀Fe₄₀B₂₀ is provided in the region that includes the interface 20 s.

For example, the second magnetic layer 20 includes both of Fe_(1-y)B_(y)(0<y≤0.3) and Co₄₀Fe₄₀B₂₀. Co₄₀Fe₄₀B₂₀ is provided in the region thatincludes the interface 20 s. Alternatively, the second magnetic layer 20may include both of (Fe_(a)Ni_(1-a))_(1-y)B_(y) (0.8≤a<1, 0<y≤0.3) andCo₄₀Fe₄₀B₂₀. Co₄₀Fe₄₀ 13 ₂₀ is provided in the region that includes theinterface 20 s.

The second magnetic layer 20 includes an amorphous portion. For example,Fe_(1-y)B_(y) (0<y≤0.3) includes an amorphous state. For example,(Fe_(a)X_(1-a))_(1-y)B_(y) (0.8≤a<1, 0<y≤0.3) includes the amorphousstate.

The second magnetic layer 20 may include the amorphous portion and acrystalline portion. For example, the region that includes the interface20 s includes the crystalline portion, and a region that does notinclude the interface 20 s includes the amorphous state.

The intermediate layer 30 disconnects the magnetic coupling between thefirst magnetic layer 10 and the second magnetic layer 20, for example.The intermediate layer 30 may include a metal, an insulator or asemiconductor, for example. For example, Cu, Au, Ag or the like may beused as the metal. In a case where the metal is used as the intermediatelayer 30, the thickness of the intermediate layer 30 is, for example,about 1 nm or more and about 7 nm or less. For example, magnesium oxide(Mg—O, etc.), aluminum oxide (Al₂O₃, etc.), titanium oxide (Ti—O, etc.),zinc oxide (Zn—O, etc.), gallium oxide (Ga—O), or the like may be usedas the insulator or the semiconductor. In a case where the insulator orthe semiconductor is used as the intermediate layer 30, the thickness ofthe intermediate layer 30 is, for example, about 0.6 nm or more andabout 2.5 nm or less. For example, a current-confined-path (CCP) spacerlayer may be used as the intermediate layer 30. In a case where the CCPspacer layer is used as the intermediate layer 30, for example, astructure in which a copper (Cu) metal path is formed in an insultinglayer of aluminum oxide (Al₂O₃) is used. For example, an MgO layerhaving a thickness of 1.5 nm may be used as the intermediate layer 30.

The functional layer 40 may include, for example, at least one of oxide,nitride and oxynitride. The functional layer 40 includes at least one ofoxide of at least one selected from a first group consisted of magnesium(Mg), aluminum (Al), silicon (Si), titanium (Ti), vanadium (V), chrome(Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu),zinc (Zn), zirconium (Zr), niobium (Nb), molybdenum (Mo), ruthenium(Ru), rhodium (Rh), palladium (Pd), silver (Ag), hafnium (Hf), tantalum(Ta), tungsten (W), tin (Sn), cadmium (Cd) and gallium (Ga), and nitrideof at least one selected from the first group, for example.

The functional layer 40 may include oxide of at least one selected froma second group consisted of magnesium, titanium, vanadium, zinc, tin,cadmium and gallium, for example. The functional layer 40 may include,for example, magnesium oxide in which low resistance is easily obtained.It is preferable that the functional layer 40 includes MgO.

The first electrode E1 and the second electrode E2 include, for example,at least one selected from aluminum (Al), an aluminum copper alloy(Al—Cu), copper (Cu), silver (Ag) and gold (Au). A current can be madeto efficiently flow in the strain sensing element 100 by using such amaterial that has a relatively small electrical resistance as the firstelectrode E1 and the second electrode E2. The first electrode E1 mayinclude a nonmagnetic material.

For example, the first electrode E1 may have a foundation layer (notshown) for the first electrode E1, a capping layer (not shown) for thefirst electrode E1, and a layer that is provided between the foundationand the capping layer and is made of at least one selected from Al,Al—Cu, Cu, Ag and Au. For example, the first electrode E1 includestantalum (Ta)/copper (Cu)/tantalum (Ta), or the like. By using Ta as thefoundation layer for the first electrode E1, it is possible to improveadhesion between a substrate 210 and the first electrode E1, forexample. Titanium (Ti), titanium nitride (TiN) or the like may be usedas the foundation layer for the first electrode E1.

By using Ta as the capping layer of the first electrode E1, it ispossible to prevent oxidization of the copper (Cu) or the like under thecapping layer. Titanium (Ti), titanium nitride (TiN) or the like may beused as the capping layer for the first electrode E1.

A current can be caused to flow in the stacked body including the firstmagnetic layer 10, the intermediate layer 30 and the second magneticlayer 20 by applying a voltage between the first electrode E1 and thesecond electrode E2. The current flows between the first magnetic layer10 and the second magnetic layer 20, for example, along the Z-axisdirection.

A pinning layer (not shown) may be provided between the first electrodeE1 and the first magnetic layer 10. The pinning layer providesunidirectional anisotropy to the first magnetic layer 10 (ferromagneticlayer) formed on the pinning layer to fix the magnetization of the firstmagnetic layer 10. The pinning layer includes, for example, anantiferromagnetic layer. The pinning layer includes, for example, atleast one selected from the group consisted of Ir—Mn, Pt—Mn, PdPtMn, andRu—Rh—Mn. The thickness of the pinning layer is set appropriately toprovide unidirectional anisotropy of sufficient strength.

As shown in FIG. 1C, the strain sensing element 100 is used in apressure sensor 200. The pressure sensor 200 includes a substrate 210and the strain sensing element 100. The substrate 210 has a flexibleregion. The strain sensing element 100 is provided on a part of thesubstrate 210.

In the specification, the “provided on” state includes a state where afirst component is provided in direct contact with a second componentand a state where a third component is interposed between the firstcomponent and the second component.

If a force 801 is applied to the substrate 210, the substrate 210 isdeformed. Strain occurs in the strain sensing element 100 according tothe deformation of the substrate 210.

In the strain sensing element 100 according to the embodiment, forexample, if the substrate 210 is deformed due to an external force,strain occurs in the strain sensing element 100. The strain sensingelement 100 converts a change of the strain into a change of anelectrical resistance.

The operation of the strain sensing element 100 functioning as a strainsensor is based on an application of an “inverse-magnetostrictioneffect” and a “magnetoresistance effect”. The “inverse-magnetostrictioneffect” is obtained in the ferromagnetic layer used in the magnetizationfree layer. The “magnetoresistance effect” occurs in the stacked film ofthe magnetization free layer, the intermediate layer and the referencelayer (for example, magnetization fixed layer).

The “inverse-magnetostriction effect” is a phenomenon in which themagnetization of a ferromagnet is changed by strain that occurs in theferromagnet. In other words, when external strain is applied to thestacked body of the strain sensing element 100, the magnetizationdirection of the magnetization free layer changes. As a result, therelative angle between the magnetization of the magnetization free layerand the magnetization of the reference layer (for example, magnetizationfixed layer) changes. Here, the change of the electrical resistance iscaused by the “magnetoresistance effect (MR effect)”. The MR effectincludes, for example, a giant magnetoresistance (GMR) effect, atunneling magnetoresistance (TMR) effect, or the like. As a currentflows in the stacked body, the change of the relative angle of themagnetization direction is read as the change of the electricalresistance, so that the MR effect occurs. For example, strain occurs inthe stacked body (the strain sensing element 100), and thus, themagnetization direction of the magnetization free layer is changed dueto the strain. Thus, the relative angle between the magnetizationdirection of the magnetization free layer and the magnetizationdirection of the reference layer (for example, magnetization fixedlayer) is changed. In other words, the MR effect occurs due to theinverse-magnetostriction effect.

In a case where the ferromagnetic material used in the magnetizationfree layer has a positive magnetostriction constant, the magnetizationdirection changes so that the angle between the magnetization directionand a tensile strain direction becomes small and the angle between themagnetization direction and a compressive strain direction becomeslarge. In a case where the ferromagnetic material used in themagnetization free layer has a negative magnetostriction constant, themagnetization direction changes so that the angle between themagnetization direction and the tensile strain direction becomes largeand the angle between the magnetization direction and the compressivestrain direction becomes small.

Hereinafter, a case where the resistance decreases when theferromagnetic materials used in the magnetization free layer and thereference layer (for example, magnetization fixed layer) respectivelyhave positive magnetostriction constants and the relative angle formedby magnetization of the magnetization free layer, the intermediatelayer, and the reference layer (for example, magnetization fixed layer)is small will be described with respect to an example of the change ofthe magnetization.

FIGS. 2A to 2C are schematic diagrams illustrating the operation of thestrain sensing element according to the first embodiment.

FIG. 2A corresponds to a state (a tensile state STt) when a tensilestress ts is applied to the strain sensing element 100. FIG. 2Bcorresponds to a state (a no-strain state ST0) when no strain is appliedto the strain sensing element 100. FIG. 2C corresponds to a state (acompressive state STc) when a compressive stress cs is applied to thestrain sensing element 100.

In FIGS. 2A to 2C, for ease of understanding, the first magnetic layer10, the second magnetic layer 20 and the intermediate layer 30 areshown, and the functional layer 40, the first electrode E1 and thesecond electrode E2 are not shown. In the example, the second magneticlayer 20 is the magnetization free layer, and the first magnetic layer10 is the magnetization fixed layer.

As illustrated in FIG. 2B, in the no-strain state ST0 (for example, aninitial state) where strain does not occur, the relative angle between amagnetization 20 m of the second magnetic layer 20 and a magnetization10 m of the first magnetic layer 10 (for example, magnetization fixedlayer) is set to a predetermined value. The magnetization direction ofthe magnetic layer in the initial state is set by an external magneticfield, a hard bias, shape anisotropy of a magnetic layer or the like,for example. In the example, the magnetization 20 m of the secondmagnetic layer 20 (magnetization free layer) and the magnetization 10 mof the first magnetic layer 10 (for example, magnetization fixed layer)intersect with each other.

As illustrated in FIG. 2A, in the tensile state STt, if the tensilestress ts is applied, strain based on the tensile stress ts occurs inthe strain sensing element 100. Here, the magnetization 20 m of thesecond magnetic layer 20 (magnetization free layer) is changed from theno-strain state ST0 so that the angle between the magnetization 20 m andthe direction of the tensile stress ts becomes small. In the exampleillustrated in FIG. 2A, in a case where the tensile stress ts isapplied, the relative angle between the magnetization 20 m of the secondmagnetic layer 20 (magnetization free layer) and the magnetization 10 mof the first magnetic layer 10 (for example, magnetization fixed layer)becomes small, compared with the no-strain state ST0. Thus, theelectrical resistance in the strain sensing element 100 is reducedcompared with the electrical resistance in the no-strain state ST0.

As illustrated in FIG. 2C, in the compressive state STc, if thecompressive stress cs is applied, the magnetization 20 m of the secondmagnetic layer 20 (magnetization free layer) is changed from theno-strain state ST0 so that the angle between the magnetization 20 m andthe direction of the compressive stress cs becomes large. In the exampleillustrated in FIG. 2C, in a case where the compressive stress cs isapplied, the relative angle between the magnetization 20 m of the secondmagnetic layer 20 (magnetization free layer) and the magnetization 10 mof the first magnetic layer 10 (for example, magnetization fixed layer)becomes large, compared with the no-strain state ST0. Thus, theelectrical resistance in the strain sensing element 100 is increased.

As described above, in the strain sensing element 100, the change of thestrain that occurs in the strain sensing element 100 is converted intothe change of the electrical resistance. In the above-describedoperation, a variation of electrical resistance (dR/R) per unit strain(dc) is referred to as a gauge factor (GF). It is possible to obtain astrain sensor of high sensitivity by using a strain sensing elementhaving a high gauge factor.

Here, as described above, the change of the electrical resistance in thestrain sensing element 100 is detected as the resistance changecorresponding to the relative angle between the magnetization 20 m ofthe second magnetic layer 20 (magnetization free layer) and themagnetization 10 m of the first magnetic layer 10 (for example,magnetization fixed layer) by the strain that occurs in the strainsensing element 100. Accordingly, in order to realize the strain sensorof high sensitivity, it is necessary to increase the change of themagnetization due to the strain and to increase the resistance changedepending on the difference of the relative angles between themagnetization of the first magnetic layer 10 and the magnetization ofthe second magnetic layer 20.

In order to easily move the magnetization of the magnetization freelayer, it is desired that the magnetization free layer represents a softmagnetic property having no strong anisotropy. In order to easily movethe magnetization of the magnetization free layer, it is favorable thatthe magnetization free layer have a structure having no magnetocrystalline anisotropy.

On the other hand, in order to show a high magnetic resistance effecthaving a predetermined value or more, it is favorable that themagnetization free layer includes a crystalline structure.

A trade-off relationship having such a characteristic may hinderrealization of improvement of the sensitivities of the strain sensingelement 100 and the pressure sensor 200.

The sensitivity of the strain sensing element 100 depends on thematerials of the first magnetic layer 10 and the second magnetic layer20, or the like, for example. A magnetic material in which a largeresistance change occurs with only a small strain is needed. However,there are relatively many magnetic materials showing an excellentcharacteristic with respect to each of the magnetostriction, softmagnetic property and magnetic resistance effect, but a magneticmaterial showing an excellent characteristic with respect to all of themagnetostriction, soft magnetic property and magnetic resistance effectis not well known. Accordingly, it may be difficult to improve thesensitivity of the strain sensing element.

On the other hand, in the strain sensing element 100 according to theembodiment, the second magnetic layer 20 includes Fe_(1-y)B_(y)(0<y≤0.3). Alternatively, the second magnetic layer 20 includes(Fe_(a)X_(1-a))_(1-y)B_(y) (0.8≤a<1, 0<y≤0.3). Alternatively, the secondmagnetic layer 20 includes both of Fe_(1-y)B_(y) (0≤y<0.3) and(Fe_(a)X_(1-a))_(1-y)B_(y) (0.8≤a<1, 0<y≤0.3). In(Fe_(a)X_(1-a))_(1-y)B_(y), X is Co or Ni.

Accordingly, it is possible to achieve the magnetostriction, softmagnetic property and magnetic resistance effect together, and toachieve improvement of the sensitivity of the strain sensing element100. Details thereof will be described later.

The amorphous state ideally does not have the magneto crystallineanisotropy, and shows an excellent soft magnetic property. It is knownthat amorphous based on Fe shows a relatively large magnetostriction. Onthe other hand, in order to achieve the magnetic resistance effect,crystallinity is needed in the interface 20 s between the secondmagnetic layer 20 and the intermediate layer 30. If the region thatincludes the interface 20 s in the second magnetic layer 20 has thecrystallinity, it is possible to achieve a higher magnetic resistanceeffect.

Thus, in a case where the region that includes the interface 20 s in thesecond magnetic layer 20 has the crystallinity and the region that doesnot include the interface 20 s in the second magnetic layer 20 is in theamorphous state, it is possible to achieve the magnetostriction, softmagnetic property and magnetic resistance effect together. In a casewhere the second magnetic layer 20 includes both of Fe_(1-y)B_(y)(0≤y<0.3) and (Fe_(a)X_(1-a))_(1-y)B_(y) (0.8≤a<1, 0<y≤0.3), and in acase where X is Co, if (Fe_(a)X_(1-a))_(1-y)B_(y) (0.8≤a<1, 0<y≤0.3) isprovided in the region that includes the interface 20 s, it is possibleto achieve the uniform magnetic resistance effect, and to achieve thesoft magnetic property and the magnetostriction together. Accordingly,it is possible to achieve improvement of the sensitivity of the strainsensing element 100.

Information about distribution of the concentration of boron (B) in thesecond magnetic layer 20 is obtained by a secondary ion massspectrometry (SIMS) analysis. The information may be obtained bycombination of transmission electron microscopy (TEM) andenergy-dispersive X-ray spectroscopy (EDX) for a cross-section. Theinformation may be obtained by an electron energy loss spectroscopy(EELS) analysis. The information may also be obtained by athree-dimensional atom probe analysis.

In the strain sensing element 100 according to the embodiment, thesecond magnetic layer 20 is provided between the intermediate layer 30and the functional layer 40. The material used in the functional layer40 is as described above, for example. Accordingly, diffusion of boron(B) is suppressed, and the boron concentration in the second magneticlayer 20 is maintained. Thus, it is possible to suppress degradation ofthe property of the second magnetic layer 20. For example, in the strainsensing element 100, it is possible to obtain a smaller coercive forceH_(c) and a higher gauge factor by the magnetic change due to largermagnetostriction.

Next, an example of an experimental result of the strain sensing element100 according to the embodiment will be described with reference to theaccompanying drawings.

FIGS. 3A to 3C are graphs illustrating an example of an experimentalresult of the strain sensing element according to the embodiment.

The second magnetic layer 20 of the strain sensing element 100 in theexamples of the experimental results in FIGS. 3A to 3C includesFe_(1-y)B_(y). Here, the examples of the experimental results relatingto a composition ratio y of boron (B) are as illustrated in FIGS. 3A to3C.

FIG. 3A is a diagram illustrating an example of the relationship betweenthe MR change ratio and the composition ratio y of boron, in the strainsensing element according to the embodiment. FIG. 3B is a diagramillustrating an example of the relationship between the coercive forceH_(c) and the composition ratio y of boron, in the strain sensingelement according to the embodiment. FIG. 3C is a diagram illustratingan example of the relationship between the gauge factor B (GFB) and thecomposition ratio y of boron.

The inventors performed evaluation of the strain sensing element 100according to the embodiment using an index called the gauge factor B(GFB). The GFB is represented by a multiplier of the MR and the magneticchange ratio due to the strain, and is proportional to the gauge factor(GF) in principal. In other words, if the GFB is relatively large, arelatively high GF is obtained. If the GFB is relatively small, arelatively low GF is obtained. As described above with reference toFIGS. 2A to 2C, it is possible to obtain a strain sensor of highsensitivity by using a strain sensing element having a high gaugefactor. In order to obtain the strain sensor of high sensitivity, ahigher GF (larger GFB) is desired.

The coercive force H_(c) is a characteristic index indicating the easeof magnetization rotation. In order to obtain the strain sensor of highsensitivity, a smaller coercive force H_(c) is desired.

As described above with reference to FIGS. 1A to 1C, the MR effect isused for reading the change of the relative angle of the magnetizationdirection as the change of the electrical resistance. In order to obtainthe strain sensor of high sensitivity, that is, in order to increase theresistance change depending on the difference of the relative anglesbetween the magnetization of the first magnetic layer 10 and themagnetization of the second magnetic layer 20, a higher MR change ratiois desired.

As illustrated in FIG. 3A, in a case where the composition ratio y ofboron is larger than 0.3, it can be understood that MR becomesrelatively small. As illustrated in FIG. 3B, in a case where thecomposition ratio y of boron is 0.3, it can be understood that arelatively small coercive force H_(c) is obtained. As illustrated inFIG. 3C, in a case where the composition ratio y of boron is 0.3, it canbe understood that the magnetization change due to strain sufficientlyoccurs and a GFB of 4000 or more is obtained. Thus, it is favorable thatthe composition ratio y of boron of the second magnetic layer 20 be 0.3or less.

On the other hand, as illustrated in FIG. 3A, in a case where the secondmagnetic layer 20 does not include boron (y=0), it can be understoodthat MR becomes relatively small. As illustrated in FIG. 3B, in a casewhere the second magnetic layer 20 does not include boron (y=0), it canbe understood that the coercive force Hc is relatively large. Asillustrated in FIG. 3C, in a case where the second magnetic layer 20does not include boron (y=0), it can be understood that the magneticchange due to strain hardly occurs and the GFB is about 0. Thus, it isfavorable that the composition ratio y of boron of the second magneticlayer 20 be larger than 0.

As illustrated in FIGS. 3A to 3C, it is favorable that the compositionratio y of boron of the second magnetic layer 20 be larger than 0 and be0.3 or less. As illustrated in FIGS. 3A to 3C, it is favorable that thecomposition ratio y of boron of the second magnetic layer 20 be 0.1 ormore and 0.3 or less.

FIGS. 4A to 4C are graphs illustrating an example of anotherexperimental result of the strain sensing element according to theembodiment.

The second magnetic layer 20 of the strain sensing element 100 in theexamples of the experimental results in FIGS. 4A to 4C includes(Fe_(a)Co_(1-a))_(1-y)B_(y). Here, examples of experimental resultsrelating to a composition ratio a of iron (Fe), in other words, relatingto a composition ratio 1-a of cobalt (Co) are as illustrated in FIGS. 4Ato 4C.

FIG. 4A is a diagram illustrating an example of the relationship betweenthe MR change ratio and the composition ratio a of iron, in the strainsensing element according to the embodiment. FIG. 4B is a diagramillustrating an example of the relationship between the coercive forceH_(c) and the composition ratio a of iron, in the strain sensing elementaccording to the embodiment. FIG. 4C is a diagram illustrating anexample of the relationship between the gauge factor B (GFB) and thecomposition ratio a of iron.

In the inspection, the composition ratio y of boron is 0.1≤y<0.3.

As illustrated in FIG. 4C, in a case where the composition ratio a ofiron is about 0.8 or more, it can be understood that a GFB of 4000 ormore is obtained. In other words, in a case where the composition ratio1-a of cobalt is about 0.2 or less, it can be understood that the GFB of4000 or more is obtained. Here, as illustrated in FIG. 4A, it can beunderstood that a relatively large MR is obtained. As illustrated inFIG. 4B, it can be understood that a relatively small coercive forceH_(c) is obtained. Thus, it is favorable that the composition ratio a ofiron of the second magnetic layer 20 be 0.8 or more. In other words, itis favorable that the composition ratio 1-a of cobalt of the secondmagnetic layer 20 be 0.2 or less.

FIGS. 5A to 5C are graphs illustrating examples of other experimentalresults of the strain sensing element according to the embodiment.

The second magnetic layer 20 of the strain sensing element 100 in theexamples of the experimental results in FIGS. 5A to 5C includes(Fe_(a)Ni_(1-a))_(1-y)B_(y). Here, examples of experimental resultsrelating to a composition ratio a of iron (Fe), in other words, relatingto a composition ratio 1-a of nickel (Ni) are as illustrated in FIGS. 5Ato 5C.

FIG. 5A is a diagram illustrating an example of the relationship betweenthe MR change ratio and the composition ratio a of iron, in the strainsensing element according to the embodiment. FIG. 5B is a diagramillustrating an example of the relationship between the coercive forceH_(c) and the composition ratio a of iron, in the strain sensing elementaccording to the embodiment. FIG. 5C is a diagram illustrating anexample of the relationship between the gauge factor B (GFB) and thecomposition ratio a of iron.

In the inspection, the composition ratio y of boron is 0.1≤y<0.3.

As illustrated in FIG. 5C, in a case where the composition ratio a ofiron is about 0.8 or more, it can be understood that a GFB of 4000 ormore is obtained. In other words, in a case where the composition ratio1-a of nickel is about 0.2 or less, it can be understood that the GFB of4000 or more is obtained. Here, as illustrated in FIG. 5A, it can beunderstood that a relatively large MR is obtained. As illustrated inFIG. 5B, it can be understood that a relatively small coercive forceH_(c) is obtained. Thus, it is favorable that the composition ratio a ofiron of the second magnetic layer 20 be 0.8 or more. In other words, itis favorable that the composition ratio 1-a of nickel of the secondmagnetic layer 20 be 0.2 or less.

FIGS. 6A to 6C are graphs illustrating examples of other experimentalresults of the strain sensing element according to the embodiment.

The second magnetic layer 20 of the strain sensing element 100 in theexamples of the experimental results in FIGS. 6A to 6C includesFe_(1-y)B_(y). Here, examples of experimental results relating to athickness t of Fe_(1-y)B_(y) are as illustrated in FIGS. 6A to 6C.

FIG. 6A is a diagram illustrating an example of the relationship betweenthe MR change ratio and the thickness t of Fe_(1-y)B_(y), in the strainsensing element according to the embodiment. FIG. 6B is a diagramillustrating an example of the relationship between the coercive forceH_(c) and the thickness t of Fe_(1-y)B_(y), in the strain sensingelement according to the embodiment. FIG. 6C is a diagram illustratingan example of the relationship between the gauge factor B (GFB) and thethickness t of Fe_(1-y)B_(y).

As illustrated in FIG. 6A, in a case where the thickness t ofFe_(1-y)B_(y) is equal to 2 nm or more, it can be understood that arelatively large MR is obtained. If the thickness t of Fe_(1-y)B_(y)becomes smaller than 2 nm, the MR is reduced. Then, a sufficientmagnetic characteristic may not be obtained. As illustrated in FIG. 6B,in a case where the thickness t of Fe_(1-y)B_(y) is 2 nm or more, it canbe understood that a relatively small coercive force H_(c) is obtained.As illustrated in FIG. 6C, in a case where the thickness t ofFe_(1-y)B_(y) is 2 nm or more, it can be understood that a GFB of 4000or more is obtained. Thus, it is favorable that the thickness t ofFe_(1-y)B_(y) be 2 nm or more.

In a case where the thickness t of Fe_(1-y)B_(y) is 2 nm or more, it ispossible to maintain the crystallinity of the region that includes theinterface 20 s in the second magnetic layer 20, and to maintain theamorphous state of the region that does not include the interface 20 sin the second magnetic layer 20.

On the other hand, as illustrated in FIG. 6C, in a case where thethickness t of Fe_(1-y)B_(y) becomes thicker than 12 nm or more, it canbe understood that the GFB becomes smaller than 4000 and becomes arelatively small value. Thus, it is favorable that the thickness t ofFe_(1-y)B_(y) be 12 nm or less. As illustrated in FIGS. 6A to 6C, it isfavorable that the thickness t of Fe_(1-y)B_(y) be 2 nm or more. Asillustrated in FIGS. 6A to 6C, it is favorable that the thickness t ofFe_(1-y)B_(y) be 2 nm or more and 12 nm or less.

FIGS. 7A to 7C are graphs illustrating examples of other experimentalresults of the strain sensing element according to the embodiment.

The second magnetic layer 20 of the strain sensing element 100 in theexamples of the experimental results in FIGS. 7A to 7C includes both ofFe_(1-y)B_(y) and Co₄₀Fe₄₀B₂₀. Here, Co₄₀Fe₄₀B₂₀ is provided in theregion that includes the interface 20 s. Examples of experimentalresults relating to a thickness t of Fe_(1-y)B_(y) are as illustrated inFIGS. 7A to 7C. In the experiment, a thickness I of Co₄₀Fe₄₀B₂₀ is setto 0 nm, 0.5 nm, and 1 nm, respectively.

FIG. 7A is a diagram illustrating an example of the relationship betweenthe MR change ratio and the thickness t of Fe_(1-y)B_(y), in the strainsensing element according to the embodiment. FIG. 7B is a diagramillustrating an example of the relationship between the coercive forceH_(c) and the thickness t of Fe_(1-y)B_(y), in the strain sensingelement according to the embodiment. FIG. 7C is a diagram illustratingan example of the relationship between the gauge factor B (GFB) and thethickness t of Fe_(1-y)B_(y).

As illustrated in FIG. 7C, in a case where Co₄₀Fe₄₀B₂₀ of several nms isprovided in the interface 20 s, similarly, it can be understood that aGFB of 4000 or more is obtained. This is because a large MR is obtained,compared with a case where only Fe≤B is used, as illustrated in FIG. 7A,and because a relatively small coercive force H_(c) is obtained asillustrated in FIG. 7B. Thus, in a case where both of Fe_(1-y)B_(y) andCo₄₀Fe₄₀B₂₀ are included in the second magnetic layer 20, it isfavorable that Co₄₀Fe₄₀B₂₀ be provided in the region that includes theinterface 20 s. By providing Co₄₀Fe₄₀B₂₀ to be easily crystallized inthe interface, it is possible to increase the MR, and to realize astrain sensor sensitive to the change of the magnetization direction.

FIGS. 8A to 8C are graphs illustrating examples of other experimentalresults of the strain sensing element according to the embodiment.

The second magnetic layer 20 of the strain sensing element 100 in theexamples of the experimental results in FIGS. 8A to 8C includes both of(Fe_(a)Ni_(1-a))_(1-y)B_(y) (0.8≤a<1, 0<y≤0.3) and Co₄₀Fe₄₀B₂₀. Here,Co₄₀Fe₄₀B₂₀ is provided in the region that includes the interface 20 s.Examples of experimental results relating to a thickness t of(Fe_(a)Ni_(1-a))_(1-y)B_(y) (0.8≤a<1, 0<y≤0.3) are as illustrated inFIGS. 8A to 8C. In the experiment, a thickness I of Co₄₀Fe₄₀B₂₀ is setto 0 nm, 0.5 nm and 1 nm, respectively.

FIG. 8A is a diagram illustrating an example of the relationship betweenthe MR change ratio and the thickness t of (Fe_(a)Ni_(1-a))_(1-y)B_(y)(0.8≤a<1, 0<y≤0.3), in the strain sensing element according to theembodiment. FIG. 8B is a diagram illustrating an example of therelationship between the coercive force H_(c) and the thickness t of(Fe_(a)Ni_(1-a))_(1-y)B_(y) (0.8≤a<1, 0<y≤0.3), in the strain sensingelement according to the embodiment. FIG. 8C is a diagram illustratingan example of the relationship between the gauge factor B (GFB) and thethickness t of (Fe_(a)Ni_(1-a))_(1-y)B_(y) (0.8≤a<1, 0<y≤0.3).

As illustrated in FIG. 8C, even in a case where Co₄₀Fe₄₀B₂₀ of severalnms is provided in the interface 20 s, similarly, it can be understoodthat a GFB of 4000 or more is obtained, which may be larger than the GFBin a configuration in which only (Fe_(a)Ni_(1-a))_(1-y)B_(y) is used.This is because a large MR is obtained, compared with a case where onlythe (Fe_(a)Ni_(1-a))_(1-y)B_(y) is used, as illustrated in FIG. 8A, andbecause a relatively small coercive force H_(c) is obtained asillustrated in FIG. 8B. In other words, this is because a small amountof increase of the coercive force H_(c) may be compensated for by theamount of increase of MR. Thus, in a case where both of(Fe_(a)Ni_(1-a))_(1-y)B_(y) and Co₄₀Fe₄₀B₂₀ are included in the secondmagnetic layer 20, it is desired that Co₄₀Fe₄₀B₂₀ be provided in theregion that includes the interface 20 s. By providing Co₄₀Fe₄₀B₂₀ to beeasily crystallized in the interface, it is possible to increase the MR,and to realize a strain sensor sensitive to the change of themagnetization direction.

FIGS. 9A to 9D are graphs illustrating examples of other experimentalresults of the strain sensing element.

FIG. 9A and FIG. 9B are graphs illustrating examples of otherexperimental results of the strain sensing element according to theembodiment.

FIG. 9C and FIG. 9D are graphs illustrating examples of otherexperimental results of a strain sensing element according to acomparative example.

The vertical axis in FIG. 9A and FIG. 9C represents the magneticthickness (the product of a saturation magnetization Bs and a thicknesst (Bs·t)). The horizontal axis in FIG. 9A and FIG. 9C represents amagnetic field. In other words, FIG. 9A and FIG. 9C represent aso-called B-H curve (B-H loop).

The vertical axis in FIG. 9B and FIG. 9D represents a constant magneticfield (in the example, magnetic field of 0). The horizontal axis in FIG.9B and FIG. 9D represents strain.

The second magnetic layer 20 of the strain sensing element 100 accordingto the embodiment in the examples of the experimental results in FIG. 9Aand FIG. 9B includes Fe_(1-y)B_(y).

The second magnetic layer 20 of the strain sensing element according tothe comparative example in the examples of the experimental results inFIG. 9C and FIG. 9D includes Co₄₀Fe₄₀B₂₀. When the graph of FIG. 9A iscompared with the graph of

FIG. 9C, the second magnetic layer 20 includes Fe_(1-y)B_(y), and thusB-H when strain is applied is significantly changed. Thus, when thegraph of FIG. 9B is compared with the graph of FIG. 9D, the secondmagnetic layer 20 includes Fe_(1-y)B_(y), and thus it is possible tosignificantly change B in the constant magnetic field due to strain.Thus, according to the magnetic material (material includingFe_(1-y)B_(y)), it is possible to realize a strain sensor of highsensitivity under the condition that a constant amount of boron isincluded.

The GFB of Co₄₀Fe₄₀B₂₀ of the strain sensing element according to thecomparative example is about 1500.

FIGS. 10A to 10D are graphs illustrating examples of results of strainsensor characteristics of the strain sensing element according to theembodiment.

In the example illustrated in FIG. 10A, with respect to the strainsensing element 100 having an element size of 20 μm×20 μm, the strainapplied to the strain sensing element 100 is set as a fixed value at 0.2(‰) intervals between −0.8 (‰) to 0.8 (‰). FIG. 10A illustratesrespective examples of results obtained by measuring magnetic fielddependency of electrical resistance in respective strains. From FIG.10A, it can be understood that the shape of an R-H loop is changed bythe value of the applied strain. This represents that in-plane magneticanisotropy of the magnetization free layer is changed by theinverse-magnetostriction effect.

FIGS. 10B to 10D represents changes of electrical resistances in thestrain sensing element 100 when an external magnetic field is fixed andstrain is continuously swept of between −0.8 (%o) and 0.8 (%o). Thestrain is swept from -0.8 (%o) to 0.8 (%o), and then, is swept from 0.8(%o) to −0.8 (%o). These results represent the strain sensorcharacteristics. In FIG. 10B, evaluation is performed by applying theexternal magnetic field of 5 Oe. In FIG. 10C, an external magnetic fieldof 2 Oe is applied to perform the evaluation. In FIG. 10D, theevaluation is performed at 0 Oe.

In the strain sensing element 100 of the embodiment, it is possible toobtain a high gauge factor by applying an appropriate bias magneticfield. The external magnetic field may also be applied by providing ahard bias to a side of the strain sensing element or providing anin-stack bias on an upper portion of the magnetization free layer. Inthe strain sensing element 100 of the embodiment, the evaluation isperformed by simply applying the external magnetic field using a coil.The gauge factor is estimated from the change of the electricalresistance with respect to the strain, from FIGS. 10B to 10D.

The gauge factor is represented by the following expression.

GF=(dR/R)/dε

From FIG. 10B, the gauge factor when the external magnetic field is 5 Oeis 3086. From FIG. 10C, the gauge factor when the external magneticfield is 2 Oe is 4418. From FIG. 10D, the gauge factor when the externalmagnetic field is 0 Oe is 5290. From these results, the maximum gaugefactor (5290) is obtained when the bias magnetic field is 0 Oe.

FIG. 11A and FIG. 11B are schematic diagrams illustrating another strainsensing element according to the first embodiment.

FIG. 11A is a schematic perspective view illustrating the strain sensingelement. FIG. 11B is a schematic cross-sectional view illustrating thestrain sensing element. In FIG. 11B, for ease of description, a firstelectrode and a second electrode are not shown.

As illustrated in FIG. 11A, a strain sensing element 100 a according tothe embodiment includes a first magnetic layer 10, a second magneticlayer 20, and an intermediate layer 30. In the example, the strainsensing element 100 a further includes a first functional layer 51, asecond functional layer 52, a first electrode E1, and a second electrodeE2. The first functional 51 and the second functional layer 52 may notbe necessarily provided. In the strain sensing element 100 describedabove with reference to FIG. 1A and FIG. 1B, the first magnetic layer 10is the magnetization fixed layer.

On the other hand, in the strain sensing element 100 a illustrated inFIG. 11A and FIG. 11B, the first magnetic layer 10 is a magnetizationfree layer.

In the example, the second electrode E2 is separated from the firstelectrode E1 in the stacking direction. The first functional layer 51 isprovided between the first electrode E1 and the second electrode E2. Thefunctional layer 51 includes a non-magnetic layer or any material exceptfor a non-magnetic material. The first magnetic layer 10 is providedbetween the first functional layer 51 and the second electrode E2. Theintermediate layer 30 is provided between the first magnetic layer 10and the second electrode E2. The second magnetic layer 20 is providedbetween the intermediate layer 30 and the second electrode E2. Thesecond functional layer 52 is provided between the second magnetic layer20 and the second electrode E2. The functional layer 52 includes anon-magnetic layer or any material except for a non-magnetic material.

In the strain sensing element 100 a illustrated in FIG. 11A and FIG.11B, the first magnetic layer 10 includes a ferromagnetic material. Thefirst magnetic layer 10 includes the same material as that of the secondmagnetic layer 20 described above with reference to FIG. 1A and FIG. 1B.

That is, in the example, the first magnetic layer 10 includesFe_(1-y)B_(y) (0<y≤0.3). Alternatively, the first magnetic layer 10includes (Fe_(a)X_(1-a))_(1-y)B_(y) (0.8≤a<1, 0<y≤0.3). Alternatively,the first magnetic layer 10 includes both of Fe_(1-y)B_(y) (0≤y<0.3) and(Fe_(a)X_(1-a))_(1-y)B_(y) (0.8≤a<1, 0<y≤0.3). In(Fe_(a)X_(1-a))_(1-y)B_(y), X is Co or Ni.

The first functional layer 51 includes the same material as that of thefunctional layer 40 described above with reference to FIG. 1A and FIG.1B. The second functional layer 52 includes the same material as that ofthe functional layer 40 described above with reference to FIG. 1A andFIG. 1B.

The second magnetic layer 20 is as described with reference to FIG. 1Aand FIG. 1B. The intermediate layer 30 is as described with reference toFIG. 1A and FIG. 1B. The first electrode E1 is as described withreference to FIG. 1A and FIG. 1B. The second electrode E2 is asdescribed with reference to FIG. 1A and FIG. 1B.

In the strain sensing element 100 a according to the embodiment, similarto the strain sensing element 100 according to the embodiment, it ispossible to obtain magnetostriction, soft magnetic property and magneticresistance effect together, and to achieve improvement of thesensitivity of the strain sensing element 100 a.

The magnetization fixed layer and the pinning layer (not shown)described above with reference to FIG. 1A and FIG. 1B may be provided toat least one of between the first functional layer 51 and the firstelectrode E1 and between the second functional layer 52 and the secondelectrode E2.

Second Embodiment

A second embodiment relates to a pressure sensor. In the pressuresensor, at least one of the strain sensing elements 100 and 100 aaccording to the first embodiment and a strain sensing element of amodification thereof is used. Hereinafter, a case where the strainsensing element 100 is used as the strain sensing element will bedescribed.

FIG. 12A and FIG. 12B are schematic perspective views illustrating apressure sensor according to the second embodiment.

FIG. 12A is a schematic perspective view. FIG. 12B is a cross-sectionalview taken along the line A1-A2 in FIG. 12A.

As illustrated in FIG. 12A and FIG. 12B, a pressure sensor 200 accordingto the embodiment includes a substrate 210 and a strain sensing element100.

As illustrated in FIG. 12A and FIG. 12B, the pressure sensor 200according to the embodiment includes a support unit 201, the substrate210, and the strain sensing element 100.

The substrate 210 is supported by the support unit 201. The substrate210 has, for example, a flexible region. The substrate 210 is, forexample, a diaphragm. The substrate 210 may be integrally formed withthe support unit 201 or may be provided separately therefrom. Thesubstrate 210 may include the same material as that of the support unit201, or a material different from that of the support unit 201. Aportion of the support unit 201 may be removed, so that the substrate210 may be the thin portion of the support unit 201.

The thickness of the substrate 210 is thinner than the thickness of thesupport unit 201. In a case where the substrate 210 and the support unit201 may include the same material, and in a case where the substrate 210and the support unit 201 are integrally formed, the thin portion is usedas the substrate 210, and the thick portion is used as the support unit201.

The support unit 201 may have a through-hole 201 h formed through thesupport unit 201 in the thickness direction, and the substrate 210 maybe provided to cover the through-hole 201 h. In such a case, forexample, the film of the material used to form the substrate 210 mayextend onto a portion of the support unit 201 other than thethrough-hole 201 h. In such a case, the portion that overlaps thethrough-hole 201 h, in the film of the material used as the substrate210, is used as the substrate 210.

The substrate 210 has an outer edge 210 r. In a case where the substrate210 and the support unit 201 include the same material and areintegrally formed, the outer edge of the thin portion is used as theouter edge 210 r of the substrate 210. In a case where the support unit201 has the through-hole 201 h formed through the support unit 201 inthe thickness direction and the substrate 210 is provided to cover thethrough-hole 201 h, the outer edge of the portion that overlaps thethrough-hole 201 h, in the film of the material used as the substrate210, is used as the outer edge 210 r of the substrate 210.

The support unit 201 may continuously support the outer edge 210 r ofthe substrate 210, or may support a part of the outer edge 210 r of thesubstrate 210.

The strain sensing element 100 is provided on the substrate 210. Forexample, the strain sensing element 100 is provided on a part of thesubstrate 210. In the example, plural strain sensing elements 100 areprovided on the substrate 210. The number of the strain sensing elementsprovided on the film part may be 1.

A first interconnect 221 and a second interconnect 222 are provided inthe pressure sensor 200 illustrated in FIG. 12A and FIG. 12B. The firstinterconnect 221 is connected to the strain sensing element 100. Thesecond interconnect 222 is connected to the strain sensing element 100.For example, an inter-layer insulating film is provided between thefirst interconnect 221 and the second interconnect 222 to electricallyinsulate the first interconnect 221 from the second interconnect 222. Avoltage is applied between the first interconnect 221 and the secondinterconnect 222, and thus, the voltage is applied to the strain sensingelements 100 through the first interconnect 221 and the secondinterconnect 222. If pressure is applied to the pressure sensor 200, thesubstrate 210 is deformed. In the strain sensing element 100, anelectrical resistance R is changed as the substrate 210 is deformed. Itis possible to sense the pressure by sensing the change of theelectrical resistance R through the first interconnect 221 and thesecond interconnect 222.

The support unit 201 may include, for example, a plate-shaped substrate.A hollow part (through-hole 201 h) is provided inside the substrate, forexample.

The support unit 201 may include, for example, a semiconductor materialsuch as silicon, a conductive material such as a metal, or an insulatingmaterial. The support unit 201 may include silicon oxide or siliconnitride, for example. The inside of the hollow part (through-hole 201 h)is in a decompression state (vacuum state), for example. The inside ofthe hollow part (through-hole 201 h) may be filled with gas such as air,or liquid. The inside of the hollow part (through-hole 201 h) may bedesigned so that the substrate 210 can be bent. The inside of the hollowpart (through-hole 201 h) may be connected to the outside atmosphere.

The substrate 210 is provided on the hollow part (through-hole 201 h). Aportion of the support unit 201 may be thinly machined to be used as thesubstrate 210. The thickness of the substrate 210 (the thickness in thez-axis direction) is thinner than the thickness of the support unit 201,the thickness in the z-axis direction.

If pressure is applied to the substrate 210, the substrate 210 isdeformed. The pressure corresponds to pressure to be sensed by thepressure sensor 200. The applied pressure includes pressure due to soundwaves, ultrasonic waves or the like. In a case where the pressure due tothe sound waves, the ultrasonic waves or the like is sensed, thepressure sensor 200 functions as a microphone.

The substrate 210 includes, for example, an insulating material. Thesubstrate 210 includes at least one selected from silicon oxide, siliconnitride and silicon oxynitride, for example. The substrate 210 mayinclude, for example, a metallic material.

The thickness of the substrate 210 is 0.1 μm or more and 3 μm or less,for example. It is favorable that the thickness be 0.2 μm or more and1.5 μm or less. The substrate 210 may include a stacked layer of asilicon oxide film having a thickness of 0.2 μm and a silicon filmhaving a thickness of 0.4 μm.

Hereinafter, an example of a method for manufacturing a pressure sensoraccording to the embodiment will be described. An example of a methodfor manufacturing a pressure sensor will be described.

FIGS. 13A to 13E are schematic cross-sectional diagrams sequentiallyillustrating the process of the method for manufacturing the pressuresensor according to the embodiment.

As illustrated in FIG. 13A, a thin film 242 is formed on a substrate 241(for example, Si substrate). The substrate 241 is used as the supportunit 201. The thin film 242 is used as the substrate 210.

For example, the thin film 242 of SiO_(x)/Si is formed on a Si substrateby sputtering. An SiO_(x) single layer, a SiN single layer or a metallayer such as Al may be used as the thin film 242. Further, a flexibleplastic material such as a polyimide or a paraxylylene-based polymer maybe used as the thin film 242, for example. A silicon on insulator (SOI)substrate may be used as the substrate 241 and the thin film 242. In theSOI, for example, a stacked film of SiO₂/Si is formed on the Sisubstrate by bonding of substrates.

As illustrated in FIG. 13B, the second interconnect 222 is formed. Inthe process, a conductive film that is used as the second interconnect222 is formed, and then, the conductive film is patterned byphotolithography and etching. In a case where an insulating film isfilled around the second interconnect 222, lift-off processing may beapplied. In the lift-off processing, for example, the insulating film isformed on the entire surface after etching the pattern of the secondinterconnect 222 and prior to peeling the resist, and then, the resistis removed.

As illustrated in FIG. 13C, the strain sensing element 100 is formed. Inthe process, a stacked film that is used as the strain sensing element100 is formed, and then, the stacked film is patterned byphotolithography and etching. In a case where the side wall of thestacked body of the strain sensing element 100 is embedded in theinsulating layer, lift-off processing may be applied. In the lift-offprocessing, for example, the insulating layer is formed on the entiresurface after patterning the stacked body and prior to peeling theresist, and then, the resist is removed.

As illustrated in FIG. 13D, the first interconnect 221 is formed. In theprocess, a conductive film that is used as the first interconnect 221 isformed, and then, the conductive film is patterned by photolithographyand etching. In a case where an insulating film is filled around thefirst interconnect 221, a lift-off processing may be applied. In thelift-off processing, the insulating film is formed on the entire surfaceafter patterning the first interconnect 221 and prior to peeling theresist, and then, the resist is removed.

As illustrated in FIG. 13E, the hollow portion 201 a is formed byperforming etching from the back surface of the substrate 241. Thus, thesubstrate 210 and the support unit 201 are formed. For example, in acase where the stacked film of SiO_(x)/Si is used as the thin film 242used to form the substrate 210, deep patterning of the substrate 241 isperformed from the back surface (the lower surface) of the thin film 242toward the front surface (the upper surface) of the thin film 242. Thus,the hollow portion 201 a is formed. For example, a double-sided alignerexposure apparatus may be used to form the hollow portion 201 a. Thus,it is possible to form the hole pattern of the resist in the backsurface to match the position of the strain sensing element 100 on thefront surface.

A Bosch process using, for example, RIE may be used to etch the Sisubstrate. In the Bosch process, for example, an etching process usingSF₆ gas and a deposition process using C₄F₈ gas are repeated. Thus,selective etching of the substrate 241 in the depth direction (theZ-axis direction) is performed while suppressing the etching of the sidewall of the substrate 241. For example, an SiO_(x) layer is used as anend point of the etching. In other words, the etching is stopped usingthe SiO_(x) layer having a selection ratio different from that of Si.The SiO_(x) layer that functions as the etching stopper layer may beused as a portion of the substrate 210. After the etching, the SiO_(x)layer may be removed, for example, by processing of anhydrous hydrogenfluoride, alcohol, or the like.

In this manner, the pressure sensor 200 according to the embodiment isformed. The other pressure sensors according to the embodiments may alsobe manufactured by similar methods.

Third Embodiment

FIG. 14 is a schematic plan view illustrating a microphone according toa third embodiment.

As illustrated in FIG. 14, a microphone 410 includes any pressure sensor(for example, the pressure sensor 200) according to the embodimentsdescribed above or a pressure sensor according to a modification ofthese pressure sensors. Hereinafter, the microphone 410 that includesthe pressure sensor 200 will be described as an example.

The microphone 410 is embedded in an end portion of a personal digitalassistant 420. The substrate 210 of the pressure sensor 200 that isprovided in the microphone 410 may be substantially parallel to, forexample, a surface of the personal digital assistant 420 where a displayunit 421 is provided. The disposition of the substrate 210 is notlimited to the above illustration and may be appropriately modified.

Since the microphone 410 includes the pressure sensor 200 or the like,it is possible to achieve high sensitivity with respect to frequenciesin a wide band.

Further, a case where the microphone 410 is embedded in the personaldigital assistant 420 is illustrated, but this is not limitative. Themicrophone 410 may also be embedded in, for example, an IC recorder, apin microphone, or the like.

Fourth Embodiment

The embodiment relates to an acoustic microphone using the pressuresensor of the embodiments described above.

FIG. 15 is a schematic cross-sectional view illustrating the acousticmicrophone according to a fourth embodiment.

An acoustic microphone 430 according to the embodiment includes aprinted circuit board 431, a cover 433, and the pressure sensor 200. Theprinted circuit board 431 includes, for example, a circuit such as anamplifier. An acoustic hole 435 is provided in the cover 433. Sound 439passes through the acoustic hole 435 to enter the inside of the cover433.

Any of the pressure sensors described in regard to the embodimentsdescribed above or a pressure sensor according to a modification ofthese pressure sensors may be used as the pressure sensor 200.

The acoustic microphone 430 responds to sound pressure. The acousticmicrophone 430 of high sensitivity is obtained by using the pressuresensor 200 of high sensitivity. For example, the pressure sensor 200 ismounted on the printed circuit board 431, and then, electrical signallines are provided. The cover 433 is provided on the printed circuitboard 431 to cover the pressure sensor 200.

According to the embodiment, it is possible to provide an acousticmicrophone of high sensitivity.

Fifth Embodiment

The embodiment relates to a blood pressure sensor using the pressuresensor of the embodiments described above.

FIG. 16A and FIG. 16B are schematic views illustrating the bloodpressure sensor according to a fifth embodiment.

FIG. 16A is a schematic plan view illustrating the skin over thearterial vessel of a human. FIG. 16B is a cross-sectional view takenalong the line H1-H2 of FIG. 16A.

In the embodiment, the pressure sensor 200 is used as a blood pressuresensor 440. The pressure sensor 200 includes any of the pressure sensorsdescribed in regard to the embodiments described above or a pressuresensor according to a modification of these pressure sensors.

Thus, it is possible to perform highly-sensitive pressure sensing by asmall size pressure sensor. The blood pressure sensor 440 can perform acontinuous blood pressure measurement by the pressure sensor 200 beingpressed onto a skin 443 over an arterial vessel 441.

According to the embodiment, it is possible to provide a blood pressuresensor of high sensitivity.

Sixth Embodiment

The embodiment relates to a touch panel using the pressure sensor of theembodiments described above.

FIG. 17 is a schematic plan view illustrating a touch panel according toa sixth embodiment.

In the embodiment, the pressure sensor 200 may be used in a touch panel450. The pressure sensor 200 includes any of the pressure sensorsdescribed in regard to the embodiments described above or a pressuresensor according to a modification of these pressure sensors. In thetouch panel 450, the pressure sensor 200 is mounted in the interior ofeither the display or outside the display.

For example, the touch panel 450 includes plural first interconnects451, plural second interconnects 452, the plural pressure sensors 200,and a controller 453.

In the example, the plural first interconnects 451 are arranged alongthe Y-axis direction. Each of the plural first interconnects 451 extendsalong the X-axis direction. The plural second interconnects 452 arearranged along the X-axis direction. Each of the plural secondinterconnects 452 extends along the Y-axis direction.

The plural pressure sensors 200 are provided respectively atintersection portions between the plural first interconnects 451 and theplural second interconnects 452. One pressure sensor 200 is used as onesensing component 200 e for sensing. Herein, the intersection portionsinclude positions where the first interconnects 451 and the secondinterconnects 452 intersect with each other and peripheral regionsthereof.

One end 261 of each of the plural pressure sensors 200 is connected toeach of the plural first interconnects 451. The other end 262 of each ofthe plural pressure sensors 200 is connected to each of the pluralsecond interconnects 452.

The controller 453 is connected to the plural first interconnects 451and the plural second interconnects 452.

For example, the controller 453 includes a first interconnect circuit453 a that is connected to the plural first interconnects 451, a secondinterconnect circuit 453 b that is connected to the plural secondinterconnects 452, and a control circuit 455 that is connected to thefirst interconnect circuit 453 a and the second interconnect circuit 453b.

The pressure sensor 200 having a small size can perform highly-sensitivepressure sensing. Thus, it is possible to realize a high definitiontouch panel.

Other than the applications described above, the pressure sensorsaccording to the embodiments described above are applicable to variouspressure sensor devices such as an atmospheric pressure sensor, an airpressure sensor of a tire.

According to the embodiments, it is possible to provide a strain sensingelement of high sensitivity, a pressure sensor, a microphone, a bloodpressure sensor, and a touch panel.

Hereinabove, the embodiments of the invention are described withreference to the specific examples. However, the invention is notlimited to the specific examples. For example, specific configurationsof the respective components such as the substrate, the strain sensingelement, the first magnetic layer, the second magnetic layer, theintermediate layer and the functional layer included in the strainsensing element, the pressure sensor, the microphone, the blood pressuresensor and the touch panel are included in the scope of the invention aslong as the specific configurations can be appropriately selected bythose skilled in the art from known techniques to realize the inventionin the same way and to achieve the same results.

Further, combinations of two or more components of the respectivespecific examples in a technically allowable range are also included inthe scope of the invention in a range without departing from the spiritof the invention.

In addition, all strain sensing elements, pressure sensors, microphones,blood pressure sensors and touch panels obtainable by an appropriatedesign modification by those skilled in the art based on the strainsensing elements, the pressure sensors, the microphones, the bloodpressure sensors and the touch panels described above as the embodimentsof the invention also are included in the scope of the invention in arange without departing from the spirit of the invention.

Various other variations and modifications can be conceived by thoseskilled in the art within the spirit of the invention, and it isunderstood that such variations and modifications are also encompassedwithin the scope of the invention.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

Hereinabove, the embodiments of the invention are described. Theembodiments of the invention may be embodied in the followingembodiments.

Embodiment 1

A strain sensing element provided on a deformable substrate, comprising:

a first magnetic layer;

a second magnetic layer including Fe_(1-y)B_(y) (0<y≤0.3), in whichmagnetization changes according to deformation of the substrate; and

an intermediate layer provided between the first magnetic layer and thesecond magnetic layer.

Embodiment 2

The element according to embodiment 1, wherein

the second magnetic layer further includes (Fe_(a)Co_(1-a))_(1-y)B_(y)(0.8≤a<1, and 0<y≤0.3), and

the (Fe_(a)Co_(1-a))_(1-y)B_(y) (0.8≤a<1, and 0<y≤0.3) is provided in aregion that includes an interface between the second magnetic layer andthe intermediate layer, the region being in the second magnetic layer.

Embodiment 3

The element according to embodiment 1, wherein

the first magnetic layer includes (Fe_(a)X_(1-a))_(1-y)B_(y) (X being Coor Ni, 0.8≤a<1, and 0<y≤0.3), and

magnetization of the first magnetic layer changes according todeformation of the substrate.

Embodiment 4

The element according to embodiment 3, wherein

a thickness of the (Fe_(a)X_(1-a))_(1-y)B_(y) (X being Co or Ni,0.8≤a<1, and 0<y≤0.3) of the first magnetic layer is 2 nm or more and 12nm or less.

Embodiment 5

The element according to embodiment 1, wherein

the first magnetic layer includes Fe_(1-y)B_(y) (0<y≤0.3), and

magnetization of the first magnetic layer changes according todeformation of the substrate.

Embodiment 6

The element according to embodiment 5, wherein

the Fe_(1-y)B_(y) (0<y≤0.3) of the first magnetic layer includes anamorphous portion.

Embodiment 7

The element according to embodiment 5, wherein

the first magnetic layer further includes (Fe_(a)X_(1-a))_(1-y)B_(y) (Xbeing Co or Ni, 0.8≤a<1, and 0<y≤0.3), and

the (Fe_(a)X_(1-a))_(1-y)B_(y) (X being Co or Ni, 0.8≤a<1, and 0<y≤0.3)is provided in a region that includes an interface between the firstmagnetic layer and the intermediate layer, the region being in the firstmagnetic layer.

Embodiment 8

The element according to embodiment 7, wherein

the (Fe_(a)X_(1-a))_(1-y)B_(y) (X being Co or Ni, 0.8≤a<1, and 0<y≤0.3)of the first magnetic layer includes an amorphous portion.

Embodiment 9

A microphone comprising a pressure sensor,

the pressure sensor including:

a support unit;

a substrate supported by the support unit, the substrate beingdeformable; and

a strain sensing element provided on the substrate,

the strain sensing element including

-   -   a first magnetic layer,    -   a second magnetic layer including Fe_(1-y)B_(y) (0<y≤0.3), in        which magnetization changes according to deformation of the        substrate, and    -   an intermediate layer provided between the first magnetic layer        and the second magnetic layer.

Embodiment 10

A blood pressure sensor comprising a pressure sensor,

the pressure sensor including:

a support unit;

a substrate supported by the support unit, the substrate beingdeformable; and

a strain sensing element provided on the substrate,

the strain sensing element including

-   -   a first magnetic layer,    -   a second magnetic layer including Fe_(1-y)B_(y) (0<y≤0.3), in        which magnetization changes according to deformation of the        substrate, and    -   an intermediate layer provided between the first magnetic layer        and the second magnetic layer.

Embodiment 11

A touch panel comprising a pressure sensor,

the pressure sensor including:

a support unit;

a substrate supported by the support unit, the substrate beingdeformable; and

a strain sensing element provided on the substrate,

the strain sensing element including

-   -   a first magnetic layer,    -   a second magnetic layer including Fe_(1-y)B_(y) (0<y≤0.3), in        which magnetization changes according to deformation of the        substrate, and    -   an intermediate layer provided between the first magnetic layer        and the second magnetic layer.

What is claimed is:
 1. A strain sensing element provided on a deformablesubstrate, comprising: a first magnetic layer; a second magnetic layerincluding Fe_(1-y)B_(y) (0<y≤0.3); and an intermediate layer providedbetween the first magnetic layer and the second magnetic layer, whereina first part of the Fe_(1-y)B_(y) (0<y≤0.3) is amorphous and a secondpart of the Fe_(1-y)B_(y) (0<y≤0.3) is not amorphous.
 2. The elementaccording to claim 1, wherein the Fe_(1-y)B_(y) (0<y≤0.3) is provided ina region that includes an interface between the second magnetic layerand the intermediate layer, the region being in the second magneticlayer.
 3. The element according to claim 1, wherein a thickness of theFe_(1-y)B_(y) (0<y≤0.3) is 2 nm or more and 12 nm or less.
 4. Theelement according to claim 1, further comprising a functional layerincluding MgO, the second magnetic layer being provided between theintermediate layer and the functional layer.
 5. The element according toclaim 1, wherein the second magnetic layer further includes Co₄₀Fe₄₀B₂₀,and the Co₄₀Fe₄₀B₂₀ is provided in a region that includes an interfacebetween the second magnetic layer and the intermediate layer, the regionbeing in the second magnetic layer.
 6. A strain sensing element providedon a deformable substrate, comprising: a first magnetic layer; a secondmagnetic layer including (Fe_(a)X_(1-a))_(1-y)B_(y) (X being Co or Ni,0.8≤a<1, and 0<y≤0.3); and an intermediate layer provided between thefirst magnetic layer and the second magnetic layer, wherein a first partof the (Fe_(a)X_(1-a))_(1-y)B_(y) (X being Co or Ni, 0.8≤a<1, and0<y≤0.3) is amorphous and a second part of the(Fe_(a)X_(1-a))_(1-y)B_(y) is not amorphous.
 7. The element according toclaim 6, wherein the (Fe_(a)X_(1-a))_(1-y)B_(y) (X being Co or Ni,0.8≤a<1, and 0<y≤0.3) is provided in a region that includes an interfacebetween the second magnetic layer and the intermediate layer, the regionbeing in the second magnetic layer.
 8. The element according to claim 6,wherein a thickness of the (Fe_(a)X_(1-a))_(1-y)B_(y) (X being Co or Ni,0.8≤a<1, and 0<y≤0.3) is 2 nm or more and 12 nm or less.
 9. The elementaccording to claim 6, wherein the second magnetic layer further includesFe_(1-y)B_(y) (0<y≤0.3).
 10. The element according to claim 6, whereinthe X is Ni, the second magnetic layer further includes Co₄₀Fe₄₀B₂₀, andthe Co₄₀Fe₄₀B₂₀ is provided in a region that includes an interfacebetween the second magnetic layer and the intermediate layer, the regionbeing in the second magnetic layer.
 11. The element according to claim1, wherein the first magnetic layer includes Fe_(1-y)B_(y) (0<y≤0.3),and magnetization of the first magnetic layer changes according todeformation of the substrate.
 12. The element according to claim 11,wherein the Fe_(1-y)B_(y) (0<y≤0.3) of the first magnetic layer isprovided in a region that includes an interface between the firstmagnetic layer and the intermediate layer, the region being in the firstmagnetic layer.
 13. The element according to claim 11, wherein athickness of the Fe_(1-y)B_(y) (0<y≤0.3) of the first magnetic layer is2 nm or more and 12 nm or less.
 14. The element according to claim 11wherein the first magnetic layer further includes(Fe_(a)X_(1-a))_(1-y)B_(y) (X being Co or Ni, 0.8≤a<1, and 0<y≤0.3), andthe (Fe_(a)X_(1-a))_(1-y)B_(y) (X being Co or Ni, 0.8≤a<1, and 0<y≤0.3)is provided in a region that includes an interface between the firstmagnetic layer and the intermediate layer, the region being in the firstmagnetic layer.
 15. The element according to claim 1, wherein the firstmagnetic layer includes (Fe_(a)X_(1-a))_(1-y)B_(y) (X being Co or Ni,0.8≤a<1, and 0<y≤0.3), and magnetization of the first magnetic layerchanges according to deformation of the substrate.
 16. The elementaccording to claim 15, wherein the (Fe_(a)X_(1-a))_(1-y)B_(y) (X beingCo or Ni, 0.8≤a<1, and 0<y≤0.3) of the first magnetic layer is providedin a region that includes an interface between the first magnetic layerand the intermediate layer, the region being in the first magneticlayer.
 17. The element according to claim 15, wherein the first magneticlayer further includes Fe_(1-y)B_(y) (0<y≤0.3).
 18. The elementaccording to claim 1, wherein the second part of the Fe_(1-y)B_(y)(0<y≤0.3) is crystalline and is disposed in a first region of the secondmagnetic layer that includes an interface between the second magneticlayer and the intermediate layer, and wherein the first part of theFe_(1-y)B_(y) (0<y≤0.3) that is amorphous is disposed in a second regionof the magnetic layer that does not include the interface.
 19. A strainsensing element provided on a deformable substrate, comprising: a firstmagnetic layer; a second magnetic layer including(Fe_(a)Ni_(1-a))_(1-y)B_(y) (0.8≤a<1, and 0<y≤0.3); and an intermediatelayer provided between the first magnetic layer and the second magneticlayer, wherein a first part of the (Fe_(a)Ni_(1-a))_(1-y)B_(y) (0.8≤a<1,and 0<y≤0.3) is amorphous and a second part of the(Fe_(a)Ni_(1-a))_(1-y)B_(y) is not amorphous.